Fig. 6: Anomaly correlation coefficient (ACC) and Root Mean Square Error (RMSE) for monthly sea ice extent (SIE) anomalies in August and September (2004–2023).

a ACC between observations and three prediction experiments: Control (blue bar), SIC-only (orange bar), and SIC-SIT (red bar). Higher ACC values indicate better prediction skills. The numbers above the bars represent the ACC values for each experiment, with asterisks indicating statistical significance at the 95% confidence level based on a Monte Carlo test. b As in a, but for the RMSE. Lower RMSE values indicate better prediction skills.